Rage Per Second

Replaced the "rage: 100" stat on your character info panel with your current RPS (Rage Per Second)
As a Guardian Druid you want to have more then 6.66 (6.11 with 2xT13) RPS so that you can keep Savage Defense up an maxium amount of time.

The Rage is generated by auto attacks and mangles, and crits of auto attacks or mangles, but you still got to hit your target so hit

Yes it does.
but you might notice the effect of the talent is not always 0.33 RPS (2 rage every 6 seconds)
sometimes it is lower becase you are not hit / exp capped. and if you miss then SotF gives on rage for that mangle